Re: [EXT] Re: [PATCH v2] mmc: core: add mmc-card hardware reset enable support

From	Richard Leitner <richard.leitner@skidata.com>
Newsgroups	linux.kernel
Subject	Re: [EXT] Re: [PATCH v2] mmc: core: add mmc-card hardware reset enable support
Date	2017-06-20 12:40 +0200
Message-ID	<tUoJJ-7ry-39@gated-at.bofh.it> (permalink)
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On 06/20/2017 11:45 AM, Linus Walleij wrote:
>> IMHO mmc-util is where the patch really stands: the enabling is OTP,
>> the programmer have to use mmc-util only once and the kernel
>> will behave accordingly.
> 
> So we should not add it to the device tree.
> 
>> Any platform vendor must check that the HW Reset pin is actually
>> Connected BEFORE enabling this feature otherwise the system may be
>> unstable. A DT Binding may be dangerous if this condition is not met
>> as well as the code execution at each MMC init is honestly redundant
>> for an OTP location of the extCSD.
> 
> I agree. So the device should be configured during production, or
> a user who know exactly what they are doing may reconfigure it
> using the mmc-utils.
> 
> Thus the kernel should just read what the device says and stay with
> that, no DT props or anything.

Ok. Thanks for that clarification to everybody involved!

Should we then add a warning/info message to the kernel if we have a
reset gpio configured in the DT, but the eMMC hasn't this OTP bit set?

Or should we just leave it as it is? (Due to the fact the reset-gpio
could be connected to an external reset chip?)

kind regards,
Richard.L

Thread

Re: [EXT] Re: [PATCH v2] mmc: core: add mmc-card hardware reset  enable support Linus Walleij <linus.walleij@linaro.org> - 2017-06-20 11:50 +0200
  Re: [EXT] Re: [PATCH v2] mmc: core: add mmc-card hardware reset  enable support Richard Leitner <richard.leitner@skidata.com> - 2017-06-20 12:40 +0200
    Re: [EXT] Re: [PATCH v2] mmc: core: add mmc-card hardware reset  enable support Linus Walleij <linus.walleij@linaro.org> - 2017-06-20 18:20 +0200

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